Cactus Shriveling and Yellow Spots: Root Rot or Drought?

A cactus shows upper pad shriveling and lower yellow spots. Full plant photo requested.

Diagnosis

Shriveling = water not reaching tissue. Two opposite causes:

• Extended soil dryness.
• Root rot from chronic overwatering—roots dead, can't supply water. Symptoms appear late.

Overwatering is more common. Cactus soil must dry halfway down pot before watering.

Action

If root rot suspected, take healthy top cuttings, let heal overnight, root in damp cactus soil. Original plant likely unsalvageable.